Updated | A new study found that eating meat regularly is associated with a 60 percent increase in the risk of heart disease, while plant-based proteins have been found to benefit the organ.

Researchers who investigated the effects of different sources of protein on the heart found that people who eat a lot of meat saw a sharp rise in the baseline risk of cardiovascular disease. However, eating protein from nuts and seeds was linked to a 40 percent reduction in cardiovascular disease.

Scientists analyzed data from over 81,000 participants of the Adventist Health Study, who filled out questionnaires about their eating patterns between 2002 and 2007. Protein from grains, processed foods, legumes, fruits and vegetables were not found to have a significant association with heart disease, according to the authors.

A classic pastrami sandwich is viewed at Katz's Delicatessen on in New York City. A new study has found that meat is less heart-healthy than plant proteins. Spencer Platt/Getty Image

The link between heart disease and diet was most apparent before participants reached old age, the authors said, leading them to believe that choosing healthy protein sources is an important factor in preventing avoidable deaths.

“Our results suggest that healthy choices can be advocated based on protein sources, specifically preferring diets low in meat intake and with a higher intake of plant proteins from nuts and seeds,” the authors said.

The teams at Loma Linda University School of Public Health in California, AgroParisTech, and the Institut National de la Recherche Agronomique in Paris, France published their findings in the International Journal of Epidemiology.

"While dietary fats are part of the story in affecting risk of cardiovascular disease, proteins may also have important and largely overlooked independent effects on risk," co-author Dr. Gary Fraser, of Loma Linda University, said in a statement. Fraser explained that the study confirmed his and his colleague’s suspicion that nuts and seeds protect the heart, while red meat carries a risk of heart disease.

The study sheds light on the perception that “bad fats” in meats and “helpful fats” in nuts are the culprits of cardiovascular disease, he added.

"This new evidence suggests that the full picture probably also involves the biological effects of proteins in these foods," he said. He also highlighted the author’s choice of differentiating between meat and nuts and seeds, rather than animal and plant proteins in general. “This research is suggesting there is more heterogeneity than just the binary categorization of plant protein or animal protein," Fraser said.

Scientists should look more deeply into how the proteins affect heart health, for instance the specific amino acids in meat proteins that lead to cardiovascular disease. Further research is also needed to determine if different protein sources affect heart disease risk factors including blood lipids, blood pressure and weight.

Dr. Jo Ann Carson, chair of the American Heart Association nutrition committee and professor of clinical nutrition at the University of Texas Southwestern Medical Center, told Newsweek: "The American Heart Association is continually reviewing emerging nutrition science, like this study, and then public health recommendations are made after weighing all of the evidence.

"The current body of research supports an overall healthy eating pattern that emphasizes fruits, vegetables and whole grains; includes low-fat dairy products, poultry, fish and nuts; and limits red meat, sweets and sugar-sweetened beverages.

"Lean meat and poultry would typically not exceed 5 oz per day on a 2,000 calorie diet, and nuts and seeds would be included at least several times per week."

The study is the latest to find a link between meat and ill-health. In 2015, the World Health Organization warned in a report that processed meats such as bacon, sausages and ham cause cancer. Eating 50 grams of processed meat, or less than two slices of bacon, increased the risk of developing colorectal cancer by 18 percent. Red meats, meanwhile, were classed as “probably carcinogenic.”

That doesn’t mean that all plant-based diets are healthy. A 2017 study published in the Journal of the American College of Cardiology warned that eating high levels of sweet food and drink, refined grains and potatoes was associated with a higher risk of heart disease.

This piece has been updated to include a comment from the Dr. Jo Ann Carson.